The present invention relates to a flat panel display device which uses a display panel, and is particularly suitable for a display device provided with a two-panel integral-type holder which holds a first display panel on one surface and a second display panel having a size smaller than a size of the first display panel on another surface.
Various types of flat panel display devices such as a display device which can perform a color display of high definition for a notebook type computer or a display monitor, a liquid crystal display device which uses a liquid crystal panel as a display panel for a mobile phone, an organic electroluminescence display device (organic EL display device) which uses electroluminescence (particularly organic electroluminescence) elements, a field emission type display device (FED) which uses field emission elements have been practically used or have been under studies for practical use thereof.
Particularly, in recent mobile phones, a display device having two screens consisting of a main screen and a sub screen thereon has been mainly mounted. In such a display device of the mobile phone, a display panel for the sub screen (a second display panel) is usually smaller in size than a display panel for the main screen (a first display panel). Further, these two display panels are mounted on the mobile phone as integral modules, wherein these display panels are accommodated into front and rear portions of a common holder. Such a holder is hereinafter referred to as a two-panel integral-type holder.
FIG. 1A to FIG. 1C are explanatory views showing a constitutional example of a two-panel integral-type holder which is popularly adopted by the mobile phones. Here, although the explanation will be made using a liquid crystal display panel as a display panel, the explanation is similarly applicable to the above-mentioned other display panels. FIG. 1A is a plan view of an accommodating surface (one surface) of the first display panel, FIG. 1B is a plan view of an accommodating surface (another surface) of the second display panel, and FIG. 1C is a side view. In this two-panel integral-type holder, a first bank-like rib RB1 which surrounds at least three sides of the periphery of the first display panel PNL1 and defines a first accommodating region is formed on a first panel accommodating surface shown in FIG. 1A. The first display panel PNL1 constitutes a display screen (screen region) by sealing liquid crystal between two glass substrates, and a drive circuit chip DRR1 for driving the first display panel is mounted on the outside of the display screen (lower side in FIG. 1A to FIG. 1C).
Further, a second bank-like rib RB2 which surrounds at least three sides of the periphery of the second display panel PNL2 and defines a second accommodating region is formed on a second panel accommodating surface shown in FIG. 1B. The second display panel PNL2 also constitutes a display screen (screen region) by sealing liquid crystal between two glass substrates, and a drive circuit chip DRR2 for driving the second display panel is mounted on the outside of the display screen (lower side in FIG. 1A to FIG. 1C). Here, in FIG. 1A to FIG. 1C, reference symbol LG indicates leg portions for mounting the two-panel integral-type holder to a body of the mobile phone using threaded holes HL. Here, in the mobile phone, it is necessary to provide a grounded conductive shield for blocking the electromagnetic wave interference (EMI) which is generated from two display panels accommodated in the inside of the casing, electronic components such as drivers, a printed circuit board, a flexible printed circuit board or the like. Accordingly, recently, display devices which will be explained hereinafter in conjunction with following FIG. 2A to FIG. 2D and FIG. 3A and FIG. 3B are used.
FIG. 2A to FIG. 2D are explanatory views of one example of the two-panel integral-type holder and, more specifically, explanatory views of a constitutional example of the two-panel integral-type holder which is molded by magnesium diecasting. FIG. 2A is a plan view of a second panel accommodating surface, FIG. 2B is a side view of a leg portion LG side, and FIG. 2C is also a side view. The second display panel PNL2 is accommodated in a second accommodating region AR2 which is defined by a second bank-like rib RB2 formed of bank-like ribs at three sides. Further, FIG. 2D is a plan view of the first panel accommodating surface. The first display panel PNL1 is accommodated in a first accommodating region AR1 which is defined by a first bank-like rib RB1 formed of bank-like ribs at three sides. Since the two-panel integral-type holder which is formed by magnesium diecasting per se has the conductivity, by grounding the two-panel integral-type holder, the holder can perform the EMI shielding function. However, the magnesium diecast product is expensive and this has been one of factors which hamper the reduction of the cost of the applied equipment such as the mobile phone. By manufacturing the two-panel integral-type holder using the resin mold explained hereinafter, it is possible to achieve the reduction of cost.
FIG. 3A to FIG. 3B are structural explanatory views of the mobile phone for explaining an example in which the two-panel integral-type holder is manufactured by resin molding. The mobile phone is of a foldable type and is constituted of body part casing MB and a display part casing DB. A transmission and reception circuit and a data processing circuit are incorporated in the body part casing MB, while a keyboard KB and functional manipulation buttons MP are mounted on a surface of the mobile phone. Although the first display panel and the second display panel are respectively accommodated in one surface (inner surface) and another surface (outer surface) of the display part casing DB, here, the first accommodating region AR1 and the second accommodating region AR2 are shown in a state that both display panels are not mounted. On a lower side of the first accommodating region AR1 (between two leg portions LG), a casing-side printed circuit board PCB which includes part which are not necessary for display is mounted.
The two-panel integral-type holder HLD has a whole body thereof formed of resin by molding (resin molding) MLD and the above-mentioned conductivity is imparted by forming a conductive layer CON on an inner surface of the mobile phone body (casing). Although the conductive layer CON which is mounted in the inside of the display part casing DB can be formed by plating, coating or any other suitable film forming method, plating is adopted here. The conductive layer CON is grounded by a printed circuit board PCB and a ground line GD at the casing side thus ensuring a shielding effect. Here, in the two-panel integral-type holder HLD, by bringing the bank-like rib RB2 which defines the second accommodating region into contact with the inner side of the display part casing DB, it is possible to support a load applied to the display part casing DB.
Here, as the literature which discloses the holder relevant to the display device of this type, Japanese Unexamined Patent Publication 2003-241170 is named, for example.